Multi-blade circulator and evaporator construction



MULTI-J SLADE CIRCULATOR ANDEVAPORATOR CONSTRUCTION Filed Feb. 24, 1958 W. A. TOBEY July 12, 1960 2 Sheets-Sheet 1 a/ffijifuf 166 w. A. TOBEY 2,944,600

MULTI-BLADE CIRCULATOR AND EVAPORATOR CONSTRUCTION July 12 1960 2 Sheets-Sheet 2 Filed Feb. 24, 1958 United States Patent C MULTI-BLADE "CIRCULATORAND EVAPORATOR CONSTRUCTION William Arthur Tobey, Manistee, Mich., assignor to Manistee Engineering Company, Manistee, Mich., a partnership g Filed Feb. 24, 1958,Ser.No. 716,898

4 Claims. (Cl. 159-25) 2,944,600 Patented July 12, .1960

2 circulator-rotors which may, for example, exceed Tthirteenfeet in diameter. It is of course particularly desirable that effective use be made of all tubesof 'theexchanger structure and that dead spots be.eliminated, to provide uniformity of operation throughout-thestructure. Many evaporators'inth'e past were built without complete recognition of designrrequirements, as a result of which the down flow well was inadequate to handle -a volume ofliquid which could be accommodated by the heat exchanger tubes. This unbalance between upward and downward flow capacities resulted in non-uniform fiow through the'heat exchangertubes'an'd insonie tubes the liquid might even be static, obviously materiallyreducing the efficiency of the heat exchange structure and corresponding efficiency of the evaporator.

The present invention contemplates the utilization of a circulator structureof high efliciency, which may Fbc readily proportioned with respect to the heat exchange structure to achieve a balanced flow, therethrough, this being accomplished by utilizing a portion of the fluid conducting tub'es of the heat exchange-structure for downviiow, supplementing. the capacity of the down-flow well,

I the number of tubes utilized for down-flow being so sesteam. The liquid normally circulates upwardly'thr ough the tubes and downwardly through the central well, and 7 preferably thecapacity of the well is to be balanced with the capacity of the tubes sothat the flow'is uniform through the tubes and balanced in upward and -down- Ward directions.

The present invention has among its objects the production of a multi-blade .circulatorwhichis so designed that it will urge fluiddownwardly. through the return well and upwardly through theftubes, the action :of the circulator being substantially balancedin both flow directions and constructed to provide arelativeuniformity of upward flow through the heatexchange structure.

Another object of the inventionis,theproduction of such a circulator structure which is so-designed that it may be utilized as a replacement in older evaporator structures, many of whichwere so designed that-a balance did not exist between the capacity of the tube structure and that of the down-flow well, to provide-an improved more balanced relation between the upward and downward flow of liquid in the evaporatorstructure with-highly improved efliciency in the operation thereo'fa A further object of the invention is theproduction of such a circulator which is so designed that adequate rigidity is provided, resulting in a smooth operating ,struc ture with a minimum of vibrations, etc.

Many other objects and advantages of the construction herein shown and described will be obvious to those skilled in the art from the disclosure herein given.

In the drawings, wherein like reference characters indicate like or'corresponding parts:

Fig. l is 'a longitudinal sectional view taken approximately on the line 1-1 of Fig. 2;

Fig. 2 is a transverse sectional view through the evaporato'rillustrated in Fig. 1' taken approximately on the line 2-2 of Fig. 1;

Fig. 3 is a sectional view taken approximately on the lected that a relative'balancebetween up-flow and downflow is achieved. Thus all tubes of the heat exchange structure are f'eficiently employedtand dead spots in the circulation of the liquid are eliminated, resulting in high efliciencyin the heat exchange operation and considerably improve'diefliciency in the operation of the evaporator;

Referring to the drawings and moreparticularly Figs.

7 1 and .2, the reference numeral 1 indicatesgenerallylan evaporator structure comprising a generally annular shaped heat exchange structure 2/ interposed between an upper housing section ,3] and a lower housing section '4. The heat exchanger structure 2 is generally annular "in shape, comprising ,an 'upper header member 5 "and "a lower"'header member 6, each of generally annular shape, having a central opening 7 and 8.therein,the headers being arranged in spaced parallel relation and operatively connected adjacent the openings 7 and 8 by a tubular member 9 defining'a down-flow well for the liquid to 'be circulated; Theheaders '5 and dare operatively connected adjaceiititlieir outer edge's by'a tubular shaped housing member 11 having ananriular shaped steam 'supply conduit 1?.v at its outer face, the housing 11 being provided with :a plurality of'slots or openings 13 therein for the passage of steam from the "supply member 12 into the interior of the exchange structure. Also connecting the headers 5 and 6 are a plurality of heat exchange tubes 14 having their ends secured to the headers 5 and 6 and the tubes thus operatively connecting the upper'and lower tively connected to the hub by a plurality of'inner'blades'" chambers formed by the housing members 3 and'4, respectively. Steam may be admitted into the supply member '12 through a suitable inlet 15 and condensate withdrawn from the exchanger structure through a re turn outlet 16. 1

bottom thereof.

hub 18 and axis of the shaft 19, the rim being opera- Positioned in the lower chamber formed by the ho'using 4 is a circulator indicated generally by the numeral 17, the circulator comprising a hub 18 of suitable construction adapted to be rigidly supported on the v'e'rti cally extending shaft 19. The circulator is, provided; with a rim 21 arranged concentrically with respect to the 22 and extending outwardly from the rim 21 is a plurality of outer blades 23.

In the embodiment of the invention illustrated, the inner blades 22 are generally L-shaped in cross-section as illustrated in detail in Fig. 3, and are suitably secured at their inner ends 24 by suitable means such as welding or the like to mounting blocks 25 adapted to be detachably secured to the hub 18 by suitable means such as bolts 26 passing through holes 27 in the blocks 25 and threaded into the hub 18, which is illustrated as being formed from a solid block of material and octagonal in cross-section to accommodate the eight blades illustrated.

The outer ends of the inner blades or spokes 22 and the inner ends of the outer blades 23 are mounted on respective flange plates 28 and 23, the adjacent surfaces of the plates being complemental to the corresponding surfaces of the rim 21, as clearly illustrated in Fig. 2, the flanges 28 and 29 being provided with aligned openings 31 therein through which common mounting means such as bolts 32 may extend and secured in place by cooperable nuts 33, four such bolts being employed with each pair of flanges. As illustrated inv Figs. 2 and 4, the outer plates 23 may each be provided with a reinforcing or stiflening bar 34 positioned at the lower face of the blade and extending transversely with respect thereto, the bar 34 being suitably attached to the blade and to the mounting flange 29 by welding or the like.

As will be apparent from a reference to Figs. 3 and 4, the inner blades or spokes 22 are pitched in the opposite direction to that of the outer blades 23, so that assuming the circulator is rotating in a counterclockwise direction as viewed in Fig. 2, the inner blade will tend to move the fluid downwardly as viewed in Fig. 1 through the well formed by the member 9, while the blades 23 are pitched to urge liquid upwardly through the tubes 14. Cooperable with the rim 17 and secured to the lower face of the tube sheet is a seal skirt 35, the latter being generally L-shaped in cross-section and having the horizontally extending flange portion 36 secured to the header plate 6.

In view of the relatively largesize of the circulator 17, the latter may be suitably braced or reinforced on the shaft 19, and as illustrated in Fig. 1, the embodiment of the invention illustrated utilizes a brace hub 37 suitably secured to the shaft 19, the hub having a generally circular shaped plate 38 extending radially therefrom to which are secured the lower ends of a plurality of brace members 39, illustrated as being in the form of circular rods threaded at their ends as indicated at 41 and '42, the upper ends being secured to the rim 21. The brace members 39 are adapted to have their ends extend through suitable collars 43 on the plate 38 and collars 44 on the-rim 21, the collars being rigidly secured, as for example by welding, to the respective members associated therewith. The rods may be secured to the collars bysuitable means such as nuts 45 threaded on the rod at opposite sides of the collars so that by adjustment of the nuts the brace members 39 may be adjusted to properly brace and support the circulator 17.

The lower end of the shaft 19 may be suitably supported with respect to the evaporator housing by suitable means, as for example, a hub member indicated generally by the numeral 46, comprising a bearing 47 carried by a plate 48 which is supported by a plurality of legs 49, illustrated as being formed from suitable stock such as angle iron and having their ends secured to mounting plates 51 and 52, the mounting plates 51 being secured, as for example, by bolting to the members 53 rigidly carried by the plate 48. In like manner the mounting plates 52 may be suitably secured to the side wall 4 of the evaporator housing by similar bolts or the like.

The invention is illustrated in Figs. '1 and 2 as applied to an evaporator structure wherein the capacity of the heat exchanger tubes is greater than that of the downflow well, as a result of which there originally existed an unbalance between the upward and downward flow paths, with a resulting variation in the flow through various heat exchanger tubes. In applying the present invention to such a structure, the diameter of the seal skirt 3S and thus of the rim 21 are so proportioned that a predetermined number of the" innermost tubes 14 have their lower ends opening inside the skirt 35 and rim 21. Thus when the circulator is rotated in a counterclockwise direction as viewed in Fig. 2, fluid will be drawn down not only through the down-flow'well but also through the innermost tubes whose lower ends open within the seal skirt 35, while the remaining tubes of the changer accommodate the upwardly flowing liquid. The diameter of the seal skirt and rim are so chosen as to provide as close a balance of downwardly flowing liquid and upwardly flowing liquid as permitted by the physical arrangement of the respective tubes, whereby a relatively balanced flow through the evaporator structure is achievedand with all tubes having a relatively uniform flow therethrough.

In the case ofnew evaporator structures, in which the heat exchanger capacity is balanced to the downflow well capacity, the seal skirt 35 may be formed as an integral part of the inner wall 9 of the heat exchange structure, which wall may be extended downwardly below the plane of the lower face of the header 6, corresponding in length to the seal skirt 35", such a construction being illustrated in Fig. 5. In such case, all of the heat exchanger tubes 14 will be'utilized in upward flow of liquid and all of the downward flow being through the well.

As illustrated in Fig. 2, the outer blades 23 taper toward their tips which tends to compensate for differences 7 in radius and thus peripheral speed of the various portions of the blades and tending to provide a relatively uniform upward flow of liquid discharged from the circulator. It will also be noted that each of the outer blades is pitched forwardly in the direction of rotation of the circulator whereby the tip portions of each blade lead the root portions, the approximate angle of the axis of the blade with respect to the radial axis of the corresponding inner blade or spoke being in the neighborhood of ten degrees in the embodiment illustrated. It will be appreciated that this forward pitch of the blade. tends to oppose centrifugal forces, thus reducing the outward thrust of liquid against the wall of the housing 4 and exchange structures may be utilized and at the same time achieve a more balanced circulation therethrough, with the elimination of static zones or areas therein.

Having thus described my invention, it will be obvious to those skilled in the art from the disclosure herein given I that various immaterial modifications may be made in the same without departing from the spirit of my invention, hence I do not wish to be understood as limiting myself to the exact form, arrangement or combination of elements herein shown and described or uses mentioned.

What I claim as new and desire to secure by Letters Patent is:

1. In an evaporator structure having upper and lower chambers and an intermediate, generally annular-shaped,-

' heat exchange structure including a plurality of tubes operatively connecting the upper and lower chambers and having .a concentric downflow well also connecting said chambers, the down-flow well having less flow capacity than said heat exchange structure, a multi-blade rotatable circulator structure positioned in the lower chamber, including a plurality of inner circulator blades and a plurality of outer circulator blades, an intermediate circulator rim member to which the adjacent ends of said inner and outercirculator blades are connected, said inner circulator blades being pitched to urge liquid downwardly through said well, and said outer circulator blades being pitched to urge liquid upwardly through adjacent tubes, an annular skirt member carried by said heat exchange structure adjacent to and in concentric relation with said intermediate circulator rim member, said annular skirt member having a diameter greater than that of the down-flow well to include the innermost tube ends whereby the inner circulator blades are operative to move liquid through said well and such innermost tubes, the latter supplementing the well to produce a more closely balanced relation between upward and downward liquid flows in the structure, said outer circulator blades having their respective axes forwardly pitched in the direction of rotation relative to corresponding radii whereby the tip portions of said outer circulator blades lead the root portions thereof to apply radially inward force to the liquid actedthereupon, in opposition to centrifugal forces on such liquid, tending to concentrate the flow of liquid through said tubes.

2. An evaporator structure as defined in claim 1,

wherein said multi-blade rotatable circulator structure is rigidly carried by and rotatable with a drive shaft concentrically arranged with respect to said evaporator structure and extending downwardly through said well into said lower chamber, a hub member positioned in said lower chamber below said multi-blade rotatable circulator structure and adapted to receive the lower end of said shaft, radially extending supporting members connected at their inner ends to said hub member and at their outer ends to the side walls of said lower chamber, a brace hub rigidly carried by said shaft and positioned above said hub member, and a plurality of brace members having their lower ends secured to said brace hub and extending upwardly and outwardly therefrom with the upper ends of said brace members being operatively connected to said circulator rim member.

3. A multi-blade circulator comprising a hub member, a concentrically arranged rim member, a plurality of radially extending inner blades having theirrespective ends connected to said hub and said rim member, and aplurality of outer blades extending outwardly from said r-im member, said inner blades being pitched to urge liquid in one axial direction and said outer blades being pitched to urge liquid in the opposite axial direction, the relative dimensions of said blades being such that the liquid flow in opposite directions is substantially balanced, said outer blades being tapered outwardly toward their tips and having the latter leading the respective root portions thereof, a brace hub axially spaced from said hub member, the latter and said brace hub being constructed for mounting on a common shaft, and a plurality of brace members extending outwardly from said bracehub toward said rim member with the free ends of said brace members secured thereto.

' 4. A multi-blade circulator comprising a hub member, a concentrically arranged rim member, a plurality of radially extending inner blades having their respective ends connected to said hub and said rim member, and a plurality of outer blades extending outwardly from said rim member, said inner blades being pitched to urge liquid in one axial direction and said outer blades being pitched to urge liquid in the opposite axial direction, the relative dimensions of said blades being such that the. liquid flow in opposite directions is substantially balanced, said outer blades being tapered outwardly toward their tips and having the latter leading the respective root portions thereof, said inner blades being generally L- shaped in cross-section, and said outer blades being generally arcuate in cross-section, each of said latter blades having a planar brace member one edge of which is positioned along an element'of the trailing face of the latter, said brace member extending outwardly from the root and said face of the associated blade and positioned in a plane extending axially of and transversely to such blade.

References Cited in the file of this patent UNITED STATES PATENTS V 

